1. Technical Field
The present invention relates to a footwear structure, which is particularly suitable for leisure or sports activities.
2. Background Art
It is notorious that a basic requirement for a footwear structure consists of the fact that it should be counter-shaped as far as possible to the shape of the user's foot in order to obtain a comfortable fit. To achieve this aim, it is usual fabricate articles of footwear in different sizes. Of course, this fact entails the drawback that the higher is the multeplicity of different sizes available for a certain article of footwear, the higher are the production, storage and transportation costs related to such article of footwear and the higher is the difficulty in accomplishing an efficient logistic management of the production and distribution stocks.
Additionally, if the user has an increasing foot size, such as a child, a given footwear article is not likely to fit the user's foot comfortably for very long. In some cases, such footwear article is barely worn before it no longer fits the user's foot. To prevent this, such footwear article can be bought in a larger size. But in this case, the user may slide frontward and backward inside the footwear structure with a reduced comfort.
Other reasons for variation of the foot size may include, for example, weight gain, weight loss, water retention or diseases. In this case, a footwear structure of a certain size could be no more comfortable for the user, who is thus obliged to buy another more comfortable article of footwear.
In order to solve this kind of problems, several adjustable fit footwear articles have been conceived.
In U.S. Pat. No. 6,279,251, it is disclosed a shoe, which includes an expansible liner that comforms to the user's foot of different sizes. The main drawback of this known solution consists of its intrinsic complexity, which very likely entails relatively high production costs. Moreover, while the upper of the shoe is somehow deformable, the size of the sole remains unchanged. This fact could reduce user's comfort, particularly if the shoe is used for sports activities. In fact, if a user with larger foot size wears the shoe, the shoe sole could be no more able to guarantee a suitable support for the user's foot.
In patent application No. TV99U000057, it is disclosed an inner sports shoe for use in ski boots, skates or the like, which comprises two separate elements interconnected by a resiliently deformable intermediate element. The main drawback of this type of sports shoes consists of the fact that they are not in itself suitable for walking. In fact, they generally comprise comprises an upper and a sole, possibly one with each other, fabricated in soft fabrics, since they are basically conceived for being associated to a rigid shell.
Other examples of adjustable fit footwear articles are disclosed in U.S. Pat. No. 5,325,614 and U.S. Pat. No. 6,138,385. In these solutions, adjustable means, which can be operated by the user, are adopted to change the size of the footwear article. Also, these footwear structures have the drawback of being provided with a relatively complex structure, thereby entailing relatively high production costs.